I Don't understand shocks?

[Scamper]

Can someone in depth explain how double adjustable shocks work. Compression and rebound. Thanks

[grt74]

I agree that you need to learn all you can on this,but youll still need to get someone to help at first to get you in the ballpark,that being said,
compression is when the shock is getting compressed or shorter,now if you have adjustable shocks you can adjust the valving which in turn can make the shock easier or harder to compress depending on what you may want to do,some also may call it a timing devise for how quick it gets on the spring
rebound,this controls how fast the shock comes out or decompresses,now as you adjust the valving on this it will decompress faster or slower depending what you may want to do
keep this in mind if you only race at 1 or two tracks you really don't need them but they are a nice tool for some small fine tuning,
one other thing also with out getting into great detail,you can build your shocks with a ton of different combinations and still have the same valving,you have bleeds,pistons,and cones ect. that you can change, also not to mention lienier,degressive and progressive curves too
if I were running locally and on a budget,i would have adjustable rf and lr,and on the lf and rr standard shocks
hope I helped some and didn't confuse you more

[Scamper]

Yes, that's gives better understanding. So your telling me..... You can make compression very stiff which will make shock very hard to compress. If I done that it would make me think shock shaft is trying very hard to resist from going into shock body which would dictate rebound. Would it not?

[grt74]

if the shaft is going into the shock body this is compression,no matter how hard it is
if the shaft is trying to come out of the shock body this is rebound,again no matter how hard it is to pull the shaft out
that being said,the above statement is referring to the compression and not rebound
again rebound is only when the shock is decompressing or the shaft is coming out of the shock body

[Matt49]

When weight transfers, it never goes to just one spring at a time. It is distributed to two or more springs and which springs is dependent on direction of weight transfer. Follow the old "heavy spring gets the weight" logic and you can understand how changing springs affects handling provided you understand what wedging and dewedging a car do to entry and exit handling.
All that a shock really is doing is controlling the speed at which the weight makes it's way to a particular spring (compression) and the speed at which the weight transfers off of the spring (rebound). So stiffer compression slows down weight transfer to that corner of the car.
Gas pressure is a topic on its own but take a look at this article for some good basic information on shocks.
http://www.afcoracing.com/tech_pages/shocks.shtml

With today's 4-bar setups, shock dynamics are much more complicated than this article even touches on but this is a good place to start.

[SS Motorsports]

Mike Farr @ Genesis Racing Shocks can give you the easiest way to understand shocks, They are a timing device, you have to figure out how fast or how slow you want each corner of your race car to work.

[grt74]

if you are wanting to understand weight transfer and all that goes with it,you should go to a set up school,it will be the best money you ever spend,i was just referring to what compression and rebound are and not so much what they do

[7uptruckracer]

Racewise was the best money I ever spent and the new Front End class is amazing as well.

[speedbuggy]

When weight transfers, it never goes to just one spring at a time. It is distributed to two or more springs and which springs is dependent on direction of weight transfer. Follow the old "heavy spring gets the weight" logic and you can understand how changing springs affects handling provided you understand what wedging and dewedging a car do to entry and exit handling.
All that a shock really is doing is controlling the speed at which the weight makes it's way to a particular spring (compression) and the speed at which the weight transfers off of the spring (rebound). So stiffer compression slows down weight transfer to that corner of the car.


This I have never been able to get my head wrapped around. Everybody always says that shocks are timing devices that slow weight transfer to a particular corner of the car. I get that when you talk about rebound. But on compression, if the shock is stiffer, wouldn't that corner of the car get MORE weight on it until it reaches its settle point dictated by the spring rate?

[7uptruckracer]

Springs are energy absorbers, and a shock trying to compress resists the weight from attempting to transfer so on the RF it is resisting the weight from the RR and LF from trying to transfer if your running more RF shock compression and rebound will hold the weight on the tire from transferring away from it

[7uptruckracer]

Here is my caveman way I explain it to people. Take your foot with a shoe. Place an egg on the ground. Stand on the egg. You now have a crushed egg. Now go take a really soft mattress topper foam place the egg under it. The foam absorbs your weight and doesnt crush the egg. Because you've absorbed the weight your foot it placing on the egg. You have changed how much you weigh (HOW MUCH THE CAR TRANSFERS) you've just changed what the egg(YOUR TIRE) sees. You can change your mattress topper foam (spring) to control your egg pressure. A shock if you stood on one will time how quick your weight will reach that topper/egg so to speak thats your compression your rebound is how long it will hold your pressure once a force like someone lifting you up remains on the egg....Its crude but the image seems to help people......sometimes unless you hate eggs

[speedbuggy]

Springs are energy absorbers, and a shock trying to compress resists the weight from attempting to transfer so on the RF it is resisting the weight from the RR and LF from trying to transfer if your running more RF shock compression and rebound will hold the weight on the tire from transferring away from it


Here is my caveman way I explain it to people. Take your foot with a shoe. Place an egg on the ground. Stand on the egg. You now have a crushed egg. Now go take a really soft mattress topper foam place the egg under it. The foam absorbs your weight and doesnt crush the egg. Because you've absorbed the weight your foot it placing on the egg. You have changed how much you weigh (HOW MUCH THE CAR TRANSFERS) you've just changed what the egg(YOUR TIRE) sees. You can change your mattress topper foam (spring) to control your egg pressure. A shock if you stood on one will time how quick your weight will reach that topper/egg so to speak thats your compression your rebound is how long it will hold your pressure once a force like someone lifting you up remains on the egg....Its crude but the image seems to help people......sometimes unless you hate eggs


Thanks for both replies. Here is what I'm really struggling to get screwed into my head right. Yes, I agree that the shock will delay the transferred weight that the spring sees, but...where did the weight go? I contend that the transferred weight now just re-routes through the shock shaft and still ends up at the tire patch. If you use the shock to slow the weight transfer through the spring, it just puts MORE weight on that wheel (through the shock) until the spring is able to support all the transferred weight. Running a higher compression shock would actually temporarily INCREASE the percentage of transferred weight that wheel sees, just like having a "temporarily stiffer" spring would. If you wanted to tighten a loose car on exit using only shocks, wouldn't you want a stiffer compression shock on the LR? This would cause the LR wheel to get transferred weight faster, not slower, and tighten up the car?

Another analogy would be transferring weight to the rear wheels though the bars. You don't really transfer any more total weight. You are just controlling how much of the weight transfers to the tire patch via the bars vs the springs.

I don't understand the egg/mattress analogy. IMO, you just spread the total weight over a larger area to keep from crushing the egg. On a car, you have four tire contact patches, that's it. No way to spread transferred weight over a larger surface area.

Sorry, not saying anybody's wrong. I just don't get it.

[7uptruckracer]

Weight transfers left to right rear to front on corner entry and front to rear on acceleration, never diagonal. With that being said your not sending through the shaft your just control how quick it allows it to come off the other corners of the car it only knows mounting points it doesn't even know a shaft is there. Twist the car up on the scales and watch the numbers change as it settles it's not immediate it takes seconds for the car to "settle" if that doesn't work try attending a chassis school

[7uptruckracer]

And my analogy wasn't for surface area just to point out your putting something that absorbs load like a spring does between something applying weight and something receiving weight

[let-r-eat]

Speedbuggy,Ball up your fist and hit the concrete wall. Then place a dampening device like a pillow or shock between your fist and the wall and throw that same punch.The same weight is transferred but the result is very different. The energy is absorbed in the absorbing device but the same punch was thrown.Shocks are about controlling the contact patches. Everything is about controlling the contact patch.The sudden jolt didn't cause the contact patch to bounce off the track. You are controlling these jolts by design of the suspension and the absorbing characteristics of the components.The suspension has a frequency at which it operates. Springs and design control this frequency.If you search for suspension frequency you will ground yourself some in the way you think now. The suspension frequency is what your talking about and not the absorption characteristics of a suspension.They are 2 entirely mutually exclusive things. A) How much weight can a corner hold *spring* B) How much absorption is on that corner *shock*

[speedbuggy]

Speedbuggy,Ball up your fist and hit the concrete wall. Then place a dampening device like a pillow or shock between your fist and the wall and throw that same punch.The same weight is transferred but the result is very different. The energy is absorbed in the absorbing device but the same punch was thrown.Shocks are about controlling the contact patches. Everything is about controlling the contact patch.The sudden jolt didn't cause the contact patch to bounce off the track. You are controlling these jolts by design of the suspension and the absorbing characteristics of the components.The suspension has a frequency at which it operates. Springs and design control this frequency.If you search for suspension frequency you will ground yourself some in the way you think now. The suspension frequency is what your talking about and not the absorption characteristics of a suspension.They are 2 entirely mutually exclusive things. A) How much weight can a corner hold *spring* B) How much absorption is on that corner *shock*

First I have ever heard of suspension frequency. I'll check that out. thx

[stock car driver]

Ill erase it for ya, pull your pantys out.

[Matt49]

If a shock is stiffer on compression, weight will transfer to that spring slower. The shock shaft doesn't hold any weight or apply pressure to the contact patch unless you are getting into some pretty high rod pressure numbers or extremely high compression.
The weight that is not transferring to that spring because of the dampening is transferring to another spring or failing to come off of another spring. But it would take insanely high compression numbers for the shock shaft to be actually loading the contact patch. The spring is the only thing that loads the contact patch to any measurable degree.
Shocks do not "absorb" weight transfer the way springs do. Shocks "dampen" weight transfer which is completely different. This is a common misconception and leads to the mindset that stiffening a shock compression is like stiffening the spring but it is completely backwards thinking. Stiffening a shock compression has the affect of softening that spring but to a lesser degree. If you want a spring to accept weight (and thereby load that corner of the car) sooner/quicker, you soften compression dampening.
Springs "absorb" weight transfer and apply it to the contact patch of the tire (how much is dependent on travel and motion ratio).
Shocks "dampen" weight transfer by changing how quickly a spring can load and unload.

[speedbuggy]

Scamper, sorry if I hi-jacked your thread.

I hope maybe you found some of this info useful.

[hpmaster]

I like posts about how shocks work, springs and weight transfer. Now after all that we turn the most complexe race car suspension in the world into a frggin gocart. The actual question I am tryin to figure out is at what point to turn it into a gokart and then release it to work again. After 30+ years experiance and a couple Race Wise classes, that I agree with about 80%+ of Mark's info, I sit quietly in the corner.

[let-r-eat]

gokart? I'm not following your thought process.Matt49 also made a nice distinction with the weight transferring but not actually going to that particular contact patch, unless dampening rates of the devices are profoundly ridiculous. LIke that pillow example between the fist and the wall. The same work was performed by you and your fist but the result to the wall and your knuckles were drastically changed, due to the dispersing of the work away from the contact point *area between knuckles contacting wall*. Coil bind setups and bumpstop setups do exactly the same by putting the sudden jolt through to the contact patch.No different than hitting a nail with a hammer and then putting a spring on top of the nail and hitting it. How far the nail sinks into the board changes dramatically. Just like trying to pound out a ball joint or anything without a solid support. All the same principle. A way of concentrating the work on the contact patch or away from the contact patch.

[7uptruckracer]

I think hes referring to the trend of locked down, binded, and bumpstopped setups. The bad ones are just overloading the wheels the guys who are truly good will know what their wheel loadings are and what the curves and ppi are on their stops etc...i guess go karts is a reference to a rigid suspension